Gravity feed can conveyors are used to transport cans from a storage or preprocessing area to a filling machine. At this stage, the cans are essentially open ended containers. Tops are attached to the cans only after filling. During transport, the cans are generally passed through a rinser which cleans various contaminants, such as dust, from the cans prior to reaching the filling machine. The conveyors normally transport the cans in a horizontal orientation, i.e., in an orientation in which the cans can roll. As the cans approach the rinser, they are rotated into a tilted position with the open ends angled downwardly, typically at about 35.degree. below horizontal. Upon exiting the rinser, the cans are passed through a rotator, essentially a short section of conveyor, which rotates the cans into an upright position.
The rinser section of a gravity feed can conveyor has always presented a slow-down in can movement. Rinsers commonly comprise a water feed line running parallel to the conveyor with a plurality of nozzles directing water in a transverse direction with respect to the direction of movement of cans on the conveyor, so that water enters the open end of the cans to effectively rinse contaminants out. The water is directed at the cans as a spray under relatively high pressure. This water spray forces the cans away from the nozzles such that the closed ends of the cans abut against a guide rail of the conveyor. This abutting action creates a friction interface which tends to slow movement of the cans.
In early systems, cans were processed at relatively slow rates, such as, for example, at 400 to 500 cans per minute. Additionally, cans were formed from steel and had a much greater weight than present day thin wall aluminum cans. At slower speeds and with greater weight, the cans could be processed through the aforementioned rinsers adequately although the rinser was often the limiting factor in conveyor line speed. In present day systems, an empty aluminum soft drink or beer can weighs less than half an ounce so that the effect of a high intensity rinser spray is greater and the gravitational force on the cans is less. Furthermore, new systems are intended to operate at speeds exceeding 1500 cans per minute so that restrictions at such rinsers are more critical.
Still further, the prior art systems are arranged to rotate the cans exiting the rinser in a single stage rotator. This rotator comprises a relatively short section of conveyor trackwork which transitions the cans from the below horizontal orientation to an upright or vertical orientation necessary to fill each can. These short rotation sections have also been found to contribute to can slow-down and, in addition, often result in damage to the cans as they are pushed into side rails of the conveyor trackwork. Such pushing and damage can cause misalignment of the cans as they enter the filling machine and result in incomplete filling of some cans.